Lawn mowing vehicle with a control unit for the motor

ABSTRACT

A lawn moving vehicle ( 1 ) is for mowing lawn along the travel path of the vehicle. The lawn moving vehicle ( 1 ) includes: at least one electric reel unit having an electric reel ( 22 ) driven by a motor ( 24 ); sensors ( 34   a - 34   c ) for detecting the travel speed of the vehicle; and a control device ( 37 ) for controlling the motor ( 24 ) according to the result of the detection by the sensors ( 34   a - 34   c ) to thereby control the rotational speed of the electric reel ( 22 ) provided to the electric reel unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 35 U.S.C. §§371 national phase conversionof PCT/JP2010/068915, filed Oct. 26, 2010, which claims priority ofJapanese Patent Application Nos. 2010-005025, 2010-005026, 2010-005027,and 2010-005028, filed on Jan. 13, 2010, the contents of which areincorporated herein by reference. The PCT International Application waspublished in the Japanese language.

FIELD OF THE INVENTION

The present invention relates to a lawn mowing vehicle.

BACKGROUND ART

As is well known, lawn mowing vehicles having reel units are classifiedroughly into lawn mowing vehicles that mow a lawn when manipulated by aworker, and lawn mowing vehicles that automatically mow a lawn withoutmanipulation of a worker (automatic lawn mowing vehicles). The formerlawn mowing vehicles are generally classified into hand-driven type(walk-behind type) lawn mowing vehicles that are operated by a workerlocated at the rear thereof, and riding lawn mowing vehicles that areoperated by a worker who boards the vehicle, and mow a lawn whiletraveling according to the operation of the worker. In contrast, thelatter lawn mowing vehicles (automatic lawn mowing vehicles) travelaccording to a result of determination of a travel path or a lawn mowingsituation that is previously set, and thus automatically mow a lawnwithout the operation of the worker.

The automatic lawn mowing vehicle typically has a larger area in which alawn can be mowed in one pass than the hand-driven type lawn mowingvehicle. As such, the hand-driven type lawn mowing vehicle is often usedto mow a lawn of a narrow range (e.g., a private yard) or to preciselymow a lawn of each green in a golf course, and a riding lawn mowingvehicle is often used to mow a lawn with a wide range (e.g. greens in agolf course or a sports ground).

An example of the hand-driven type lawn mowing vehicle is disclosed inU.S. Pat. No. 7,111,443, in which a motor is driven by power suppliedfrom a battery, and a lawn mowing unit is operated by a driving force ofthe motor. Further, an example of a lawn mowing unit is disclosed inPublished Japanese Translation No. H05-503207 of the PCT InternationalPublication, which includes an adjustment mechanism capable of adjustinga mowing height of grass, without complicating or interfering with themechanism.

An example of the riding lawn mowing vehicle is disclosed in JapaneseUnexamined Patent Application, First Publication No. 2000-139157, whichis configured to be able to move up and down reel units using hydrauliccylinders. In detail, the riding lawn mowing vehicle is allowed toswitch back pressure for elevating cylinders, which move up and downthree reel units disposed in the front of the vehicle, depending on theslope or unevenness of a working surface, thereby realizing stable workwith mowing the lawn while still maintaining a traveling speed withoutdelay of downward movement of the reel units.

Such a riding lawn mowing vehicle is disclosed in Japanese UnexaminedPatent Application, First Publication No. H09-074818 (hereinafter“JP-H09-074818”), in which a plurality of electrode parts detectingcropped traces are installed on a bottom portion of the vehicle; achange in voltage between when the electrode parts are electricallyconducted by contact with grass and when the electrode parts areinsulated by non-contact with the grass is detected; and a cropped-traceboundary that is a boundary between an uncropped area and a cropped areais detected using the detected result. Further, an automatic travelworking vehicle is disclosed in Japanese Unexamined Patent Application,First Publication No. S62-070916, in which a predetermined range infront of the vehicle is captured by a camera during radiating strobelight, and predetermined treatment is performed on a captured image,thereby detecting a boundary between an untreated work area and atreated work area. Furthermore, a method of classifying vitality ofvegetation into “soundness,” “caution,” “warning,” and “diseased” from ahistogram obtained by analyzing reflection information (brightnessinformation image) from the vegetation caught by a video camera, andevaluating a variation in the vitality of vegetation which is easilyunderstood by a human being is disclosed in Japanese Unexamined PatentApplication, First Publication No. 2004-213627.

Such an automatic lawn mowing vehicle is disclosed in Japanese PatentNo. 2896017 (hereinafter “JP 2896017”), which is configured so as to beable to discriminate a boundary located on each of left and right sidesof a vehicle body (a boundary between a treated work area in which alawn has been mowed and an untreated work area in which a lawn has notbeen mowed), and to automatically balance positions in a widthwisedirection of the vehicle body with regard to these boundaries, therebyenabling a lawn to be properly mowed.

Further, an example of the riding lawn mowing vehicle is disclosed inJapanese Unexamined Patent Application, First Publication No. H11-089377(hereinafter “JP-H11-089377”), in which reel units are elevated usinghydraulic cylinders. In detail, the riding lawn mowing vehicle includesthree reel units disposed in the front thereof and two reel unitsdisposed on left and right sides thereof When the reel units arelowered, oil channels for the hydraulic cylinders, which elevate the tworeel units disposed on left and right sides of the vehicle, are blockedto prevent the two reel units from being lowered. Thereby, a mowingwidth can be narrowed.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, to neatly mow a lawn at a uniform height, mowing conditions ofthe lawn need to be constantly maintained. This is because, if themowing conditions are changed depending on a place, uneven cutting ofthe lawn is caused, which reduces mowing quality. To secure constantmowing conditions of the lawn, it is necessary to constantly maintain aratio of a traveling speed of the vehicle to a rotational speed of acutter (cutter mowing a lawn, which is called a reel) installed on areel unit.

Fundamentally, the conventional lawn mowing vehicles constantly maintaina traveling speed while rotating a cutter at a constant rotationalspeed, thereby preventing mowing quality from being reduced.Particularly, the riding lawn mowing vehicles have difficulty inprecisely controlling the rotational speed of the cutter because boththe wheels and the cutter are driven using a driving force of theengine, or because the cutter is driven using a driving force of themotor. As such, in the related art, the position of an accelerator ismechanically set to be constant on the assumption that the rotationalspeed of the cutter is made constant. Thereby, both the rotational speedof the cutter and the traveling speed of the vehicle are made constant.

Further, in a conventional riding lawn mowing vehicle in which aplurality of elevatable reel units are installed at different positionsin the frontward/rearward direction of the vehicle, an elevatingposition of a reel unit (hereinafter referred to as a “front reel unit”)installed in the front of the vehicle and an elevating position of areel unit (hereinafter referred to as a “rear reel unit”) installed inthe rear of the vehicle are required to be matched with each other. Thisis because, when the front reel unit and the rear reel unit are elevatedat the same time, a portion of the lawn which is mowed only by the frontreel unit and a portion of the lawn which is mowed only by the rear reelunit are generated, and thus an overmowed or undermowed portion isgenerated.

In order to match the elevating positions of the front reel unit and therear reel unit with each other, the rear reel unit need only be elevatedat a position at which the vehicle travels from a position at which thefront reel unit is elevated by an interval between the front reel unitand the rear reel unit. However, since it is difficult to preciselycontrol the conventional riding lawn mowing vehicle that elevates thereel unit using a hydraulic cylinder, the rear reel unit is elevatedafter a predetermined time has elapsed while elevating the front reelunit, regardless of the traveling speed of the vehicle.

However, the ground on which the grass grows is not necessarily flat,but may have ups and downs. For example, the greens of a golf course arefull of ups and downs formed intentionally in order to increase a levelof difficulty of play. When the grass, which grows on the ground havingsuch ups and downs, is mowed by a lawn mowing vehicle, a traveling speedof the lawn mowing vehicle is automatically changed depending on the upsand downs of the ground even if an accelerator position is mechanicallyset to be constant. Thereby, there is a problem in that a mowing qualityis reduced.

Further, when the traveling speed of the lawn mowing vehicle isautomatically changed, a difference between the elevating positions ofthe front reel unit and the rear reel unit is caused. Thereby, themowing quality is also reduced.

Incidentally, determination of, e.g., a growth state of the lawn andmanagement of a height of the grass are basically performed on the basisof experience of a worker. That is, the worker manages the height of thegrass by visually determining the growth state of the lawn, adjusting aheight adjusting mechanism installed on the lawn mowing vehicledepending on the growth state, and mowing the lawn. However, all workerswho operate the lawn mowing vehicle cannot necessarily properlydetermine the growth state of the lawn and perform proper managementcorresponding to the determined result. For this reason, if the growthstate of the lawn is automatically detected and the detected result isprovided to a worker, this is very useful to the worker, and isconsidered to be able to increase an added value of the lawn mowingvehicle.

Furthermore, when the lawn is mowed, it is necessary to minimize achance of the lawn being mowed again at a treated work area at which thelawn has already been mowed. This is because, when the mowing isrepeated several times, a portion of the lawn which is unnecessarilymowed is generated, and thus uneven mowing occurs, which reduces themowing quality. Since the lawn mowing vehicles disclosed inJP-H09-074818 and JP 2896017 above detects the boundary between thetreated work area where the lawn has been mowed and the untreated workarea at which the lawn has not yet been mowed, if the lawn mowingvehicle travels so as not to mow the lawn of the treated work area alongthe boundary, the mowing equality of the lawn is considered to be ableto be prevented from being reduced.

However, in the case in which the lawn is mowed so that a width of thelawn to be mowed is narrower than a mowing width of the vehicle, evenwhen the vehicle travels along the boundary, many portions of the lawnwhich are mowed several times are generated. As such, the mowing qualityof the lawn is reduced. As in the lawn mowing vehicle disclosed inJP-H11-089377, if the mowing width is narrowed, the portions of the lawnwhich are mowed several times can be reduced. As such, it is possible toprevent the mowing quality of the lawn from being reduced. However, theconventional lawn mowing vehicle that elevates the reel units using thehydraulic cylinders has a problem in that there is a risk of an adverseeffect that the grass is withered by leaked oil. Further, theconventional lawn mowing vehicle basically elevates and rotates all thereel units in the same way, and thus has a problem in that unnecessaryconsumption of energy is frequent.

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the related art, and the present inventionis directed to a lawn mowing vehicle, in which a high quality of lawnmowing is possible even with a change in traveling speed of the vehicle.Further, the present invention is directed to a lawn mowing vehicle, inwhich, even when the traveling speed is changed, the elevating positionsof the reel units can be matched with each other, and the lawn can bemowed with a high quality.

Further, the present invention is directed to a lawn mowing vehiclehaving a higher added-value, capable of automatically measuring a growthstate of a lawn, and providing useful information in managing the lawn.

In addition, the present invention is directed to a lawn mowing vehiclecapable of performing a high quality of lawn mowing with low powerconsumption without causing an adverse effect such as withering ofgrass.

Means for Solving the Problem

According to a first aspect of the present invention, a lawn mowingvehicle (1, 2), which mows a lawn along a travel path, includes: atleast one electric reel unit (13 a, 13 b, 14) having a rotating blade(22) driven by a motor (24); a speed detection unit (34 a to 34 c, 37,40) detecting a traveling speed of the vehicle; and a control unit (37,40) that controls the motor depending on the detected result of thespeed detection unit, thereby controlling a rotational speed of therotating blade installed on the electric reel unit. The rotating bladeis configured so that a rotational shaft thereof is set in aleftward/rightward direction of the vehicle with respect to thetraveling direction, and the speed detection unit detects the travelingspeed of the vehicle on the basis of revolutions per unit time of wheelsinstalled on the vehicle and effective diameters of the correspondingwheels.

When revolutions per unit time of a plurality of wheels installed on thevehicle are different, the speed detection unit may obtain an averagevalue of the revolutions per unit time of the plurality of wheels.

The control unit may control a rotational speed of the rotating blade onthe basis of a number of blades of the electric reel unit and a mowingpitch of the lawn (a target interval of the lawn) which is arbitrarilyset in advance in addition to the detected result of the speed detectionunit.

The control unit may control a rotational speed of the rotating blade sothat the rotational speed of the rotating blade is proportional to thedetected result of the speed detection unit.

The control unit may control a rotational speed of the rotating blade sothat the rotational speed of the rotating blade varies step-by-step withrespect to the detected result of the speed detection unit.

According to a second aspect of the present invention, a lawn mowingvehicle (4, 402), which has first and second reel units (13 a, 13 b, 14)disposed at positions that are different from each other in afrontward/rearward direction thereof with respect to a travelingdirection, includes: a first elevating mechanism that elevates the firstreel unit using an electric actuator (26 a, 26 b); a second elevatingmechanism that elevates the second reel unit using an electric actuator;a speed detection unit (34 a to 34 c, 37, 40) that detects a travelingspeed of the vehicle; and a control unit (437, 440) that controls thefirst and second elevating mechanisms depending on the detected resultof the speed detection unit so that an elevating position of the firstreel unit is consistent with that of the second reel unit. The first andsecond reel units are electric reel units, each of which has a rotatingblade (22) driven by a motor (24) and is configured so that a rotationalshaft of the rotating blade is set in the leftward/rightward directionthat intersects the traveling direction of the vehicle, and the controlunit changes a time from when the first reel unit begins to be elevatedto when the second reel unit begins to be elevated depending to thedetected result of the speed detection unit.

Further, the lawn mowing vehicle related to the second aspect of thepresent invention may include an input unit (427) that inputs aninstruction of whether or not to perform automatic elevation controlthat is control of matching elevating positions of the first and secondreel units with each other. The control unit may perform the automaticelevation control when the instruction to perform the automaticelevation control is received from the input unit.

When there is no instruction to perform the automatic elevation control,the control unit may control the first and second reel units so as to beindividually elevated depending on the instruction input from the inputunit.

According to a third aspect of the present invention, a lawn mowingvehicle (5, 502), which has at least one of first and second reel units(13 a, 13 b) disposed at positions that are different from each other ina leftward/rightward direction thereof with respect to a travelingdirection, includes: a first elevating mechanism (25 a, 26 a) thatelevates the first reel unit using an electric actuator (26 a); a secondelevating mechanism (25 b, 26 b) that elevates the second reel unitusing an electric actuator (26 b); and a control unit (537, 540) thatcontrols the first and second elevating mechanisms and individuallyelevates the first and second reel units. The vehicle includes aselection unit (527) that selects an elevating reel unit from among thefirst and second reel units, and the control unit performs control ofelevating the reel unit selected by the selection unit.

The first and second reel units may be electric reel units, each ofwhich has a rotating blade (22) driven by a motor (24) and is configuredso that a rotational shaft of the rotating blade is set in theleftward/rightward direction that intersects the traveling direction ofthe vehicle.

Effects of the Invention

According to the present invention, since the rotational speed of therotating blade installed on the electric reel unit is controlled bycontrolling the motors depending on the detected result of the speeddetection unit, even when the traveling speed of the lawn mowing vehicleis changed, a high quality of lawn mowing is possible.

Further, the state of the lawn mowed by the rotating blade is detectedby the detection sensor, and a predetermined process is performed on thedetected result of the detection sensor. Thereby, the growth dataindicating the growth situation of the lawn is generated, and thegenerated growth data is displayed on the display unit. As such, it ispossible to provide a higher value-added lawn mowing vehicle that canprovide useful information in managing the lawn.

According to the present invention, the first and second elevatingmechanisms are controlled depending on the detected result of the speeddetection unit so that the elevating position of the first reel unit isconsistent with that of the second reel unit. As such, even when thetraveling speed of the lawn mowing vehicle is changed, a high quality oflawn mowing is possible.

Further, the control unit can control the first and second elevatingmechanisms, each of which has the electric actuator, to individuallyelevate the first and second reel units, and elevate and operate aminimum necessary reel unit to mow the lawn. As such, the high qualityof lawn mowing can be performed with low power consumption withoutcausing an adverse effect such as withering of the grass.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an external appearance of a lawnmowing vehicle according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of essential units ofa power system and a control system in the lawn mowing vehicle accordingto the first embodiment of the present invention.

FIG. 3 is a diagram showing an example of a relation between thetraveling speed and the revolutions per minute of the electric reel inthe lawn mowing vehicle according to the first embodiment of the presentinvention.

FIG. 4 is a block diagram showing a configuration of essential units ofa power system and a control system in a lawn mowing vehicle accordingto a second embodiment of the present invention.

FIG. 5 is a side view schematically showing an internal configuration offront reel units 313 a and 313 b according to a third embodiment of thepresent invention.

FIG. 6A is a view showing one example of displayed contents of a displaydevice 427 provided to a lawn mowing vehicle 4 according to a fourthembodiment of the present invention.

FIG. 6B is a view showing one example of the displayed contents of thedisplay device 427 provided in the lawn mowing vehicle 4 according tothe fourth embodiment of the present invention.

FIG. 6C is a view showing one example of the displayed contents of thedisplay device 427 provided in the lawn mowing vehicle 4 according tothe fourth embodiment of the present invention.

FIG. 7A is a view showing one example of displayed contents of a displaydevice 527 provided in a lawn mowing vehicle 5 according to a fifthembodiment of the present invention.

FIG. 7B is a view showing one example of the displayed contents of thedisplay device 527 provided in the lawn mowing vehicle 5 according tothe fifth embodiment of the present invention.

FIG. 7C is a view showing one example of the displayed contents of thedisplay device 527 provided in the lawn mowing vehicle 5 according tothe fifth embodiment of the present invention.

FIG. 7D is a view showing one example of the displayed contents of thedisplay device 527 provided in the lawn mowing vehicle 5 according tothe fifth embodiment of the present invention.

EMBODIMENTS OF THE INVENTION

Hereinafter, a lawn mowing vehicle according to embodiments of thepresent invention will be described in detail with reference to thedrawings.

(First Embodiment)

FIG. 1 is a perspective view showing an external appearance of a lawnmowing vehicle according to a first embodiment of the present invention.Hereinafter, the lawn mowing vehicle will be described using a ridinglawn mowing vehicle as an example, but the present embodiment may alsobe applied to a hand-driven lawn mowing vehicle. As shown in FIG. 1, thelawn mowing vehicle 1 of the present embodiment includes two frontwheels 11 a and 11 b and one rear wheel 12, and two front reel units(electric reel units) 13 a and 13 b and one rear reel unit (electricreel unit) 14, all of which are supported on a frame 10. The lawn mowingvehicle 1 travels via the front wheels 11 a and 11 b and the rear wheel12, and mows a lawn via the front reel units 13 a and 13 b and the rearreel unit 14 along a travel path. The lawn mowing vehicle 1 is a hybridtype lawn mowing vehicle that travels using power of its engine and mowsa lawn using the power of, for example, a motor.

A seat 15 on which a worker sits is installed on approximately a middleupper portion of the frame 10. A steering wheel 16 is installed on afront upper portion relative to the seat 15. A reverse accelerator pedal17, an advance accelerator pedal 18, and a brake pedal 19 are installedon a front lower portion relative to the seat 15. The worker sitting onthe seat 15 manipulates the steering wheel 16, and thus a travelingdirection of the lawn mowing vehicle 1 is determined. The workermanipulates the reverse accelerator pedal 17, the advance acceleratorpedal 18, and the brake pedal 19, and thus backward movement, forwardmovement, stopping, and a traveling speed of the lawn mowing vehicle 1are determined.

The front wheels 11 a and 11 b are installed respectively on aright-hand front lower portion and a left-hand front lower portion ofthe frame 10, are driven by power of a hydraulic motor directly coupledto the engine E, and are supported on the frame 10 in aleftward/rightward direction so as to be able to rotate about arotational shaft. The rear wheel 12 is installed on a middle rear lowerportion of the frame 10, is driven by power of the hydraulic motor inthe same way as the front wheels 11 a and 11 b in the event ofthree-wheel driving, and freely rotates in the event of two-wheeldriving. However, unlike the front wheels 11 a and 11 b, the rear wheel12 is configured so as to be able to fluctuate in the leftward/rightwarddirection in proportion to an amount of rotation of the steering wheel16. Since the rotational shaft of the rear wheel 12 also fluctuates inaccordance with the leftward/rightward fluctuation of the rear wheel 12,the traveling direction of the lawn mowing vehicle 1 is changed by therotation of the steering wheel 16. The lawn mowing vehicle 1 is equippedwith a mechanism (so-called power steering) that assists in steering thesteering wheel 16 using the power of the engine E.

Each of the front wheels 11 a and 11 b and the rear wheel 12 employs awide tire whose shoulder is formed in a smooth curved surface. This isintended to avoid damage to the lawn by distributing weight and stressof the lawn mowing vehicle 1 which are applied to the front wheels 11 aand 11 b and the rear wheel 12. Further, each of the front wheels 11 aand 11 b and rear wheel 12 employs a tire with no groove formed therein.This is intended to prevent a striped pattern from being formed on thelawn by producing a treaded portion (portion at which no groove isformed) and an untreaded portion (portion at which the groove isformed).

The front reel units 13 a and 13 b are elevatably supported in the frontof the front wheels 11 a and 11 b, respectively, and are lowered to mowthe lawn in front of the front wheels 11 a and 11 b in contact with theground. Each of the front reel units 13 a and 13 b includes a frontroller 21, an electric reel (rotating blade) 22, a rear roller (notshown), and a motor 24. The front roller 21 is substantially acylindrical member in which a rotational shaft thereof is installed inthe leftward/rightward direction of the vehicle and in which a pluralityof grooves, each of which is formed in a circumferential direction, arealso formed in an axial direction, and are disposed in front of theelectric reel 22. The front roller 21 is installed to arrange the grassthat has not yet been mowed by the electric reel 22, and to support thefront reel unit 13 a or 13 b, which is in a lowered state, on theground.

The electric reel 22 is a substantially cylindrical member in which aplurality of spiral blades for mowing the lawn are formed on a sidethereof, whose rotational shaft is set in the leftward/rightwarddirection of the vehicle, and which are driven by the motor 24. Theelectric reel 22 is interposed between the front roller 21 and the rearroller (not shown), and is disposed so as to be higher than the frontroller 21 and the rear roller (not shown) by a height of the grass thathas been mowed. A height position of the electric reel 22 in relation tothe front roller 21 and the rear roller (not shown) can be preciselyadjusted, for instance, within a range of several millimeters to tens ofmillimeters. The rear roller (not shown) is a substantially cylindricalmember in which grooves as in the front roller 21 are not formed, and isinstalled to support the front reel unit 13 a or 13 b, which is in thelowered state, on the ground, like the aforementioned front roller 21.

The frame 10 is provided with a support arm 25 a that extends from amiddle portion in a rightward direction and a support arm 25 b thatextends from the middle portion in a leftward direction, at a frontportion thereof The support arm 25 a fluctuably supports the front reelunit 13 a around the rotational shaft in a frontward/rearward directionof the vehicle at a right-hand end thereof, and the support arm 25 bfluctuably supports the front reel unit 13 b around the rotational shaftin the frontward/rearward direction of the vehicle at a left-hand endthereof. As such, even when the ground is inclined in thefrontward/rearward direction of the vehicle, the front reel units 13 aand 13 b can be inclined in response to the inclination.

The support arms 25 a and 25 b are provided with electric cylinders 26 aand 26 b as actuators. When the electric cylinder 26 a is expanded orcontracted, the right-hand end of the support arm 25 a moves in anupward/downward direction. Thereby, the front reel unit 13 a is raisedor lowered. Similarly, when the electric cylinder 26 b is expanded orcontracted, the left-hand end of the support arm 25 b moves in theupward/downward direction. Thereby, the front reel unit 13 b is raisedor lowered. FIG. 1 shows that the front reel unit 13 a is in a raisedstate, while the front reel unit 13 b is in a lowered state.

The rear reel unit 14 is elevatably supported between the front wheels11 a and 11 b and the rear wheel 12, and is lowered to mow grass infront of the rear wheel 12 in contact with the ground. Like the frontreel units 13 a and 13 b, the rear reel unit 14 includes a front roller21, an electric reel (rotating blade) 22, a rear roller (not shown), anda motor 24, and is raised or lowered by an elevating mechanism (notshown) having, for instance, an electric cylinder (electric actuator)similar to the electric cylinders 26 a and 26 b. Like the front reelunits 13 a and 13 b, the rear reel unit 14 is also fluctuably supportedaround the rotational shaft in the frontward/rearward direction of thevehicle, and can be inclined in response to an inclination of the groundin the frontward/rearward direction of the vehicle.

Further, a touch panel type display device (e.g., a liquid crystaldisplay device) 27 (an input unit, a display unit, and a selection unit)is installed on the right-hand in front of the seat 15 (right-hand sideof the steering wheel 16). The display device 27 receives instructionsfrom a worker, and simultaneously displays various pieces of informationsuch as information showing a current state of the lawn mowing vehicle1. The elevation of each of the front reel units 13 a and 13 b and therear reel unit 14, and a start and stop of the electric reel 22installed on each reel unit are controlled in response to theinstruction input by the worker operating the display device 27. Theinformation displayed on the display device 27 includes information suchas information showing a traveling speed of the lawn mowing vehicle 1,rotational speeds of the electric reels 22 installed on the front reelunits 13 a and 13 b and the rear reel unit 14, and a growth situation ofthe lawn. Further, a lighting device 28 illuminating the front of thelawn mowing vehicle 1 is installed between the advance accelerator pedal18 and the brake pedal 19 below the steering wheel 16.

FIG. 2 is a block diagram showing a configuration of essential units ofa power system and a control system in the lawn mowing vehicle accordingto the first embodiment of the present invention. Note that, in FIG. 2,the same symbols are used for components corresponding to those shown inFIG. 1. As shown in FIG. 2, the lawn mowing vehicle 1 includes ahydraulic pump 31 and an alternator 32. The power system is generallydivided into a traveling system S1 and a steering system S2 that aredriven by hydraulic pressure transferred from the hydraulic pump 31, anda work system S3 driven by electric current supplied from the alternator32. In FIG. 2, a path of the hydraulic pressure transferred from thehydraulic pump 31 is indicated by a thick solid line, whereas a path ofthe electric current supplied from the alternator 32 is indicated by athin solid line. Further, a path of a signal related to a control systemis indicated by a thin broken line.

The hydraulic pump 31 is driven by the power of the engine E, andgenerates the hydraulic pressure driving the traveling system Si and thesteering system S2. The alternator 32 includes an alternating-currentgenerator 32 a driven by the engine E, a converter (AC/DC) 32 bconverting alternating current from the alternating-current generator 32a into direct current, and a diode 32 c, and generates direct current,for instance, having a voltage of 24 V.

The traveling system S1 includes a hydraulic circuit 33 that transfersthe hydraulic pressure transferred from the hydraulic pump 31 to thefront wheels 11 a and 11 b and the rear wheel 12. Further, the frontwheels 11 a and 11 b and the rear wheel 12 are equipped with sensors(speed detection units) 34 a, 34 b and 34 c that detect the revolutionsper unit time (e.g. revolutions per minute), respectively. Detectedresults of the sensors 34 a to 34 c are output to a control device 37,which will be described below. The steering system S2 includes ahydraulic circuit 35 in which the hydraulic pressure is transferred fromthe hydraulic pump 31 to a power steering mechanism that assists insteering the steering wheel 16.

The electric current supplied from the alternator 32 is input into awork system S3, a lighting device 28, a booster circuit 36, and acontrol device 37 (a control unit, a speed detection unit, and a dataprocessing unit). The work system S3 includes the electric cylinders 26a and 26 b that are shown in FIG. 1, the electric cylinder 26 c that isnot shown in FIG. 1, the electric reel 22 and the motor 24 that areinstalled on each of the front reel units 13 a and 13 b and the rearreel unit 14, switches 38 a, 38 b and 38 c, and motor drivers 39 a to 39c. The switches 38 a, 38 b and 38 c are configured so that switchingconditions thereof are controlled by the control device 37, and providean electrical interruption or conduction state between the alternator 32and the electric cylinders 26 a, 26 b and 26 c. The switch is oneexample of components of a switching mechanism. Thus, a cylinder drivermade up of a semiconductor may be used.

When the switches 38 a and 38 b enter a closed state (ON state), thedirect current from the alternator 32 is supplied to the electriccylinders 26 a and 26 b. Thereby, the electric cylinders 26 a and 26 bare driven, and thus the front reel units 13 a and 13 b are raised orlowered. Although not shown in FIG. 1, the electric cylinder 26 c, whichelevates the rear reel unit 14, is also equipped with the switch 38 c(switch whose switching condition is controlled by the control device37) similar to the switches 38 a and 38 b.

The motor drivers 39 a, 39 b and 39 c drive the respective motors 24installed on the front reel units 13 a and 13 b and the rear reel unit14 under the control of the control device 37. Thereby, a rotationalspeed of the reel 22 installed on each of the front reel units 13 a and13 b and the rear reel unit 14 is controlled. The booster circuit 36 isa circuit that enables a voltage of the direct current from thealternator 32 to be boosted by a factor of about 10. The boosted voltageis input into each of the motor drivers 39 a, 39 b and 39 c.

The control device 37 controls operation of the work system S3 of thelawn mowing vehicle 1 in response to an instruction input via thedisplay device 27, and displays information representing a current stateof the lawn mowing vehicle 1 (e.g. information representing thetraveling speed and rotational speeds of the electric reels 22) on thedisplay device 27. In detail, when an elevating instruction of the frontreel units 13 a and 13 b and the rear reel unit 14 is input via thedisplay device 27, the control device 37 controls ON and OFF states ofthe switches 38 a, 38 b and 38 c. Further, when a driving instruction ofthe electric reels 22 installed on the front reel units 13 a and 13 band the rear reel unit 14 is given via the display device 27, thecontrol device 37 outputs control signals for the motor drivers 39 a to39 c, thereby controlling the rotational speeds of the electric reels22.

The control device 37 controls the rotational speeds of the electricreels 22 installed on the front reel units 13 a and 13 b and the rearreel unit 14 on the basis of detected results of the sensors 34 a to 34c. This is intended to realize a high quality of lawn mowing even whenthe traveling speed of the lawn mowing vehicle 1 automatically variesdue to ups and downs of the ground despite the lawn mowing vehicle 1being driven so as to have a constant traveling speed.

When the detected result of the sensor 34 c which indicates revolutionsper minute of the rear wheel 12 is n [rpm], and an effective diameter ofthe rear wheel 12 is d [mm], the control device 37 obtains the travelingspeed v [km/h] of the lawn mowing vehicle 1 from Equation (1) below.v=(d/10⁶)×π×60×n  (1)

To simplify the description, an example in which the traveling speed ofthe lawn mowing vehicle 1 is obtained on the basis of only the detectedresult of the sensor 34 c is described. However, the traveling speed maybe obtained on the basis of the detected results of all the sensors 34 ato 34 c. When the detected results of the sensors 34 a to 34 c aredifferent, an average value of the detected results is preferably set tothe traveling speed.

The control device 37 controls the motor drivers 39 a to 39 c so thatthe rotational speeds of the electric reels 22 installed on the frontreel units 13 a and 13 b and the rear reel unit 14 are proportional tothe traveling speed obtained from Equation (1) or vary step-by-step inrelation to the traveling speed obtained from Equation (1). Whether thecontrol is performed so as to be proportional or vary step-by-step inrelation to the traveling speed is properly determined in considerationof, for example, performance of the motors 24 or the motor drivers 39 ato 39 c.

The rotational speeds of the electric reels 22 are not necessarilydetermined by only the traveling speed of the lawn mowing vehicle 1. Inaddition to the traveling speed of the lawn mowing vehicle 1, thecontrol is performed based on the number of blades provided on eachelectric reel 22 and a mowing pitch (a target mowing interval of thelawn). In detail, assuming that the number of blades of the electricreel 22 is m [pieces], and the mowing pitch is p [mm], the controldevice 37 controls the revolutions per minute r [rpm] of the electricreel 22 to the revolutions per minute shown in Equation (2) below.r=(v×10⁶/60)/(m×p)  (2)

where p is the mowing interval of the lawn [mm].

FIG. 3 is a diagram showing an example of a relation between thetraveling speed and the revolutions per minute of the electric reel inthe lawn mowing vehicle according to the first embodiment of the presentinvention. In FIG. 3, the traveling speed of the lawn mowing vehicle 1is shown as an x-axis, and the revolutions per minute of the electricreel 22 is shown as a y-axis. In FIG. 3, the relation between thetraveling speed and the revolutions per minute of the electric reel whenthe mowing pitches are set to 3 mm, 3.5 mm, 4 mm, 4.5 mm, and 5 mm isshown in a graph.

When the rotational speed of the electric reel 22 is controlled so as tobe proportional to the traveling speed, the graphs of the respectivemowing pitches are indicated as “3 mm,” “3.5 mm,” “4 mm,” “4.5 mm,” and“5 mm” by a legend of the right side of the figure. In contrast, whenthe rotational speed of the electric reel 22 is controlled so as to varyin a stepwise fashion in relation to the traveling speed, the graphs ofthe respective mowing pitches are indicated as “3 mm STP,” “3.5 mm STP,”“4 mm STP,” “4.5 mm STP,” and “5 mm STP” by the legend of the right sideof the figure.

Referring to FIG. 3, in either of the case in which the rotational speedof the electric reel 22 is controlled so as to be proportional to thetraveling speed and the case in which the rotational speed of theelectric reel 22 is controlled so as to vary in a stepwise fashion inrelation to the traveling speed, it can be understood that, as thetraveling speed increases, the revolutions per minute of the electricreel 22 is controlled so as to increase. Further, when the travelingspeed of the lawn mowing vehicle 1 is constant, it can be understoodthat the revolutions per minute of the electric reel 22 is controlled soas to be increased in inverse proportion to the mowing pitch.

Next, an operation of the lawn mowing vehicle 1 in the aforementionedconfiguration will be described in brief. When a worker sitting on theseat 15 of the lawn mowing vehicle 1 operates a start key of the engine,the engine E starts. When the engine E starts, the hydraulic pump 31 isdriven, and thus hydraulic pressure for driving the traveling system S1and the steering system S2 is generated. Further, the alternator 32 isdriven by the engine E, thereby generating direct current. The directcurrent generated by the alternator 32 is supplied to the work systemS3, the lighting device 28, the control device 37, and the boostercircuit 36. A voltage boosted by the booster circuit 36 is supplied tothe work system S3.

The worker operates the steering wheel 16 along with the reverseaccelerator pedal 17, the advance accelerator pedal 18, or the brakepedal 19, and drives the lawn mowing vehicle 1 to a position at which alawn is to be mowed. When the lawn mowing vehicle 1 arrives at theposition at which the lawn is to be mowed, the worker operates thedisplay device 27 to give an instruction to lower the front reel units13 a and 13 b and the rear reel unit 14. Then, the control device 37outputs control signals for the switches 38 a, 38 b and 38 c, and thusthe front reel units 13 a and 13 b and the rear reel unit 14 arelowered. Thereby, the lawn is mowed along a travel path of the lawnmowing vehicle 1 by the front reel units 13 a and 13 b and the rear reelunit 14.

During mowing of the lawn, the control device 37 obtains a travelingspeed of the lawn mowing vehicle 1 from a detected result of the sensor34 c (revolutions per minute of the rear wheel 12) using Equation (1)above. Then, the control device 37 obtains revolutions per minute of theelectric reel 22 from Equation (2) above using the obtained travelingspeed, and controls the motor drivers 39 a to 39 c. Thereby, the controldevice 37 controls the revolutions per minute of the electric reels 22installed on the front reel units 13 a and 13 b and the rear reel unit14. In this way, rotational speeds of the electric reels 22 arecontrolled in response to the traveling speed of the lawn mowing vehicle1.

As described above, in the present embodiment, since the rotationalspeeds of the electric reels 22 installed on the front reel units 13 aand 13 b and the rear reel unit 14 are controlled by controlling themotors 24 based on the detected result of, for instance, the sensor 34c, even when the traveling speed of the lawn mowing vehicle 1 ischanged, a high quality of lawn mowing in which the height of the grassis uniform is possible. Further, the mowing vehicle 1 of the presentembodiment is a hybrid type lawn mowing vehicle that travels using thepressure of the hydraulic pump driven by the power of the engine andmows the lawn using the power of the electric motors. Since the mowingvehicle 1 can reduce a risk of oil leakage compared to a conventionallawn mowing vehicle that mows a lawn using power of a hydraulic pump, itcan reduce the risk of withering the grass caused by oil, compared tothe conventional lawn mowing vehicle.

(Second Embodiment)

FIG. 4 is a block diagram showing a configuration of essential units ofa power system and a control system in a lawn mowing vehicle accordingto a second embodiment of the present invention. Note that, in FIG. 4,the same symbols are used for the same blocks as the blocks shown inFIG. 2. The lawn mowing vehicle 2 is an electric lawn mowing vehiclethat uses power of, e.g., a motor to travel and to mow a lawn. Anexternal appearance of the lawn mowing vehicle 2 of the presentembodiment is almost the same as that of the lawn mowing vehicle 1 ofthe first embodiment shown in FIG. 1.

As shown in FIG. 4, the lawn mowing vehicle 2 of the present embodimentincludes a battery B in place of the engine E, the hydraulic pump 31,and the alternator 32 of FIG. 2. Further, the lawn mowing vehicle 2includes a traveling system S11 and a steering system S12 in place ofthe traveling system S1 and the steering system S2 of FIG. 2, and isequipped with a control device 40 (a control unit, and a speed detectionunit) in place of the control device 37. In FIG. 4, a path along whichelectric current is supplied from the battery B is indicated by a thinsolid line, and a path of a signal involved in the control system isindicated by a thin broken line.

The battery B supplies direct current to the traveling system S11, thesteering system S12, and a work system S3, as well as a lighting device28, a booster circuit 36, and the control device 40. The battery Bgenerates direct current, for instance, having a voltage of 48 V. Thetraveling system S11 includes motors 41 a, 41 b and 41 c driving frontwheels 11 a and 11 b and a rear wheel 12 respectively, and motor drivers42 a to 42 c driving the respective motors 41 a to 41 c.

Each of the motor drivers 42 a to 42 c is supplied with the directcurrent from the battery B, and a control signal for the control device40 is supplied to each of the motor drivers 42 a to 42 c. The motordrivers 42 a to 42 c drive the respective motors 41 a to 41 c undercontrol of the control device 40. In the present embodiment, the frontwheels 11 a and 11 b and the rear wheel 12 are also equipped withsensors 34 a, 34 b and 34 c that detect the revolutions per unit time(e.g. revolutions per minute), respectively.

The steering system S12 includes a motor 43, a motor driver 44, and asteering sensor 45, and assists in steering a steering wheel 16 underthe control of the control device 40. The motor 43 transfers power tothe steering wheel 16, thereby realizing power steering that assists insteering the steering wheel 16. The motor driver 44 drives the motor 43on the basis of the control signal output from the control device 40.The motor driver 44 is also supplied with the direct current from thebattery B. The steering sensor 45 detects an amount of rotation of thesteering wheel 16, and outputs the detected result to the control device40.

Like the control device 37 shown in FIG. 2, the control device 40controls operation of the work system of the lawn mowing vehicle 2 inresponse to an instruction input via the display device 27. That is, thecontrol device 40 controls elevations of the front reel units 13 a and13 b and the rear reel unit 14 on the basis of the instructions inputvia the display device 27, and rotational speeds of the electric reels22 installed on the front reel units 13 a and 13 b and the rear reelunit 14 on the basis of detected result of the sensors 34 a to 34 c.

Further, the control device 40 controls the motor driver 44 on the basisof a detected result of the steering sensor 45, thereby realizing thepower steering that assists in steering the steering wheel 16.Furthermore, the control device 40 controls an amount of fluctuation atwhich the rear wheel 12 fluctuates in a leftward/rightward direction onthe basis of the detected result of the steering sensor 45, and controlsthe motor drivers 42 a to 42 c in response to an amount of operation of,e.g., the reverse accelerator pedal 17. Thereby, the control device 40controls backward movement, forward movement, stopping, and a travelingspeed of the lawn mowing vehicle 2.

Like the lawn mowing vehicle 1 of the first embodiment, the lawn mowingvehicle 2 having the aforementioned configuration is also configured sothat the motors 24 are controlled by the control device 40 in responseto the detected result of, e.g., the sensor 34 c, and thereby therotational speeds of the electric reels 22 installed on the front reelunits 13 a and 13 b and the rear reel unit 14 are controlled. As such,even when the traveling speed of the lawn mowing vehicle 2 is changed, ahigh quality of lawn mowing in which grass has a constant height ispossible.

Further, the lawn mowing vehicle 2 of the present embodiment is anelectric lawn mowing vehicle that uses the power of the motors to traveland to mow the lawn, and thus requires no engine. As such, the lawnmowing vehicle 2 can be made light, formation of wheel tracks can beprevented, and damage to the lawn can be reduced. Further, the lawnmowing vehicle 2 of the present embodiment does not require anyhydraulic pressure for driving the traveling system S11 and the steeringsystem S12, and thus has no possibility of oil leakage. As such,withering of the grass caused by leaked oil does not occur.

While the lawn mowing vehicle according to the embodiments of thepresent invention has been described, the present invention is notlimited to the embodiments. The lawn mowing vehicle can be freelymodified within the spirit and scope of the present invention. In theembodiments, the lawn mowing vehicle having the electric reels 22 whoserotational shafts are installed in the leftward/rightward direction ofthe vehicle has been described. However, the present invention may beapplied to lawn mowing vehicles having electric reels whose rotationalshafts are installed in an upward/downward direction.

Further, not all the rotational speeds of the electric reels 22installed on the front reel units 13 a and 13 b and the rear reel unit14 are essentially controlled so as to be the same. Thus, the rotationalspeeds of the electric reels 22 may be individually controlled inresponse to the traveling speed. For example, when the lawn mowingvehicle travels around a curve, the rotational speed of the electricreel 22 installed on the front reel unit 13 a may be controlled on thebasis of the detected result of the sensor 34 a, the rotational speed ofthe electric reel 22 installed on the front reel unit 13 b may becontrolled on the basis of the detected result of the sensor 34 b, andthe rotational speed of the electric reel 22 installed on the rear reelunit 14 may be controlled on the basis of the detected result of thesensor 34 c.

Furthermore, in the above embodiments, an example in which therevolutions per minute of the front wheels 11 a and 11 b and the rearwheel 12 are detected by the sensors 34 a to 34 c, respectively, and thetraveling speed is obtained from the detected results has beendescribed. However, in the lawn mowing vehicle 1 according to the firstembodiment, the traveling speed may be obtained by the revolutions perminute and a flow rate of the traveling hydraulic motor and theeffective diameters of the front wheels 11 a and 11 b and the rear wheel12.

(Third Embodiment)

A third embodiment of the present invention will be described based onFIG. 5. The lawn mowing vehicle 3 related to the present embodiment isdifferent from the lawn mowing vehicle 1 related to the first embodimentin that the lawn mowing vehicle 3 includes a detection sensor Ddetecting the state of a lawn. Note that, in the lawn mowing vehicle 3,the same symbols are used for constituent elements common with the lawnmowing vehicle 1, and thus a repeated description will be omitted here.Hereinafter, as the lawn mowing vehicle, a riding lawn mowing vehiclewill be described as an example. However, the present embodiment may bealso applied to a hand-driven lawn mowing vehicle.

The lawn mowing vehicle 3 related to the present embodiment isconfigured so that the configuration other than the internalconfiguration of front reel units 313 a and 313 b is the same as that ofthe lawn mowing vehicle 1 shown in FIGS. 1 and 2. The internalconfiguration of front reel units 313 a and 313 b is shown in FIG. 5 ina schematic side view. As shown in FIGS. 1 and 5, each of the front reelunits 313 a and 313 b includes a front roller 21, an electric reel(rotating blade) 22, a rear roller 23, and a motor 24.

The front roller 21 is a substantially cylindrical member whoserotational shaft is set in a leftward/rightward direction of the vehicleand in which a plurality of grooves, each of which is formed in acircumferential direction, are also formed in an axial direction, andare disposed in front of the electric reel 22. The front roller 21 isinstalled to arrange the grass that has not yet been mowed by theelectric reel 22, and to support one of the front reel units 313 a and313 b, which are in a lowered state, on the ground. Height adjustmentmechanisms J, which adjust a relative height position between the frontroller 21 and the electric reel 22, are installed on left-hand andright-hand ends of the front roller 21.

Each height adjustment mechanism J is made up of a bolt J1 extending ina vertical direction and a nut J2 fitted around the bolt J1. By turningthe nut J2 to change a height position of the nut J2 with respect to thebolt J1, the relative height position between the front roller 21 andthe electric reel 22 can be adjusted. By adjusting the relative heightposition between the front roller 21 and the electric reel 22, a mowingheight (a target length of grass) can be subjected to preciseadjustment, for instance, within a range of several millimeters to tensof millimeters.

The electric reel 22 is interposed between the front roller 21 and therear roller 23, and is disposed so as to be higher than the front roller21 and the rear roller 23 by a height of the grass that has been mowed.The rear roller 23 is a substantially cylindrical member in whichgrooves are formed as in the front roller 21, and is installed tosupport the front reel unit 313 a or 313 b, which is in the loweredstate, on the ground, like the aforementioned front roller 21.

Further, a detection sensor D, which detects the state of grass that hasnot yet been mowed by the electric reel 22, is installed inside thefront reel unit 313 a or 313 b. Further, the detection sensor D isinstalled in front of the front roller 21 (in front of the electric reel22) inside the front reel unit 313 a or 313 b, and detects at least oneof a height of the grass, a color of the grass, and a standing state ofthe grass. As a sensor detecting the height of the grass, for example, atouch sensor may be used. As a sensor detecting the color of the grass,an imaging device such as a color charge-coupled device (CCD) may beused. Further, as a sensor detecting the standing state of the grass, asensor detecting reflectance of light illuminated on the grass may beused. The standing state of the grass is detected using the fact thatthe reflectance is increased when the grass is lies flat and is reducedwhen the grass stands. Hereinafter, to simplify the description, thedetection sensor D is defined as the sensor that detects the height ofthe grass.

In the present embodiment, the rear reel unit 314 includes, similar tothe front reel units 313 a and 313 b, a front roller 21, an electricreel (rotating blade) 22, a rear roller 23, and a motor 24, and iselevated by an elevating mechanism (not shown) having, for instance, anelectric cylinder similar to the electric cylinders 26 a and 26 b. Likethe front reel units 313 a and 313 b, the rear reel unit 314 issupported so as to be able to fluctuate around a rotational shaft in afrontward/rearward direction of the vehicle, and can be inclinedaccording to an inclination of the ground in a frontward/rearwarddirection of the vehicle.

The lawn mowing vehicle 3 related to the present embodiment includes acontrol device 337 in place of the control device 37 shown in FIG. 2.Further, the lawn mowing vehicle 3 includes a display device 327 inplace of the display device 27 shown in FIG. 2. The control device 337controls rotational speeds of the electric reels 22 installed on thefront reel units 313 a and 313 b and the rear reel unit 314 on the basisof detected results of the sensors 34 a to 34 c. Further, the controldevice 337 controls the electric cylinders 26 a, 26 b and 26 c so thatelevating positions of the front reel units 313 a and 313 b areconsistent with that of the rear reel unit 314. The controls areintended to realize a high quality of lawn mowing even when a travelingspeed of the lawn mowing vehicle 3 automatically varies due to ups anddowns of the ground despite the lawn mowing vehicle 3 being driven so asto have a constant traveling speed.

Further, the control device 337 performs a predetermined process on adetected result of the detection sensor D, and then generates growthdata indicating a growth state of the lawn. In detail, the controldevice 337 generates a state map, which indicates the state of the lawnat each place at which the lawn is mowed each time the lawn is mowed.The lawn is typically mowed at the same place each day or every severaldays using the lawn mowing vehicle 3. Thus, the control device 337detects a previous height of the grass at a place (region) at which thelawn is repetitively mowed whenever the lawn is mowed using thedetection sensor D, and generates the state map indicating a planardistribution of the detected heights (distribution at the place at whichthe lawn is mowed). The growth data is output to the display device 327.Thereby, information that indicates the growth state of the lawn isdisplayed on the display device 327.

It is preferable that, in addition to the detection sensor D, at leastone of temperature and humidity sensors (environmental sensors) beinstalled, and the control device 337 perform a process of causingtemperature or humidity detected by the temperature sensor or thehumidity sensor to be included in the growth data. By performing such aprocess, information indicating the temperature or the humidity is addedto the growth data representing the growth state of the lawn. As such,it is possible to provide a worker with more useful information.

During mowing of the lawn, the control device 337 obtains traveldistances of the front wheels 11 a and 11 b and the rear wheel 12 fromthe detected results of the sensors 34 a to 34 c, thereby obtaining atravel path of the lawn mowing vehicle 3. Then, the obtained travel pathand the detected result of the detection sensor D are mapped to eachother, and the state map indicating the planar distribution of theheights of the grass is generated. Thereby, the growth data isgenerated. Further, the control device 337 performs the process ofcausing the temperature or the humidity detected by the temperaturesensor or the humidity sensor to be included in the growth data asneeded. During mowing of the lawn, under the control of the controldevice 337, a traveling speed of the lawn mowing vehicle 3 is obtainedfrom the detected result of the sensor 34 c, and revolutions per minuteof the electric reels 22 installed on the front reel units 313 a and 313b and the rear reel unit 314 are changed in response to the obtainedtraveling speed.

When the mowing of the lawn is terminated and the worker gives a displayinstruction of the growth data to the display device 327, the state mapgenerated by the control device 337 is displayed on the display device327. Among the growth data generated by the control device 337, apredetermined number of data elements generated most recently are storedin the control device 337. As such, when the worker gives apredetermined instruction to the display device 327, the growth datagenerated before being stored can be displayed on the display device327.

As described above, in the present embodiment, the state of the lawn isdetected by the detection sensor D, and the predetermined process isperformed on the detected result. Thereby, the growth data indicatingthe growth situation of the lawn is generated, and the generated growthdata is displayed. As such, it is possible to provide useful informationto the worker in managing the lawn. Further, in the present embodiment,since the rotational speeds of the electric reels 22 installed on thefront reel units 313 a and 313 b and the rear reel unit 314 arecontrolled according to the detected results of, e.g., the sensor 34 c,even when the traveling speed of the lawn mowing vehicle 3 is changed, ahigh quality of lawn mowing in which the grass has a constant height ispossible. In addition, the lawn mowing vehicle 3 of the presentembodiment is a hybrid type lawn mowing vehicle that travels using thepressure of the hydraulic pump driven by the power of the engine andmows the lawn using the power of the electric motors. Since the lawnmowing vehicle 3 can reduce a risk of oil leakage compared to aconventional lawn mowing vehicle that mows a lawn using power of ahydraulic pump, it can reduce the risk of withering the grass caused byoil, compared to the conventional lawn mowing vehicle.

(Modification of Third Embodiment)

Like the lawn mowing vehicle 2 related to the second embodiment, amodification of the lawn mowing vehicle 3 related to the presentembodiment may be a lawn mowing vehicle 302 that includes a battery B inplace of the engine E, the hydraulic pump 31, and the alternator 32. Inthis case, the lawn mowing vehicle 302 is equipped with a travelingsystem S11 and a steering system S12 in place of the traveling system S1and the steering system S2. Further, the lawn mowing vehicle 302 isequipped with a control device (data processing unit) 340 in place ofthe control device 337.

The lawn mowing vehicle 302 is also configured so that the state of alawn is detected by a detection sensor D, so that a predeterminedprocess is performed on the detected result, so that growth dataindicating a growth situation of the lawn is generated, and so that thegenerated growth data is displayed. As such, it is possible to provideuseful information to a worker in managing the lawn. Further, in thepresent embodiment, rotational speeds of electric reels 22 installed onfront reel units 313 a and 313 b and a rear reel unit 314 are controlledaccording to detected results of, e.g., a sensor 34 c. As such, evenwhen a traveling speed of the lawn mowing vehicle 302 is changed, a highquality of lawn mowing in which the grass has a constant height ispossible.

(Fourth Embodiment)

Hereinafter, a fourth embodiment of the present invention will bedescribed based on FIG. 6. The lawn mowing vehicle 4 related to thefourth embodiment of the present invention is similar to the lawn mowingvehicle 1 shown in FIGS. 1 and 2, except that it includes a controldevice 437 in place of the control device 37 shown in FIG. 2 and adisplay device 427 in place of the display device 27 shown in FIG. 2.Note that the same symbols are used for constituent elements common withthe lawn mowing vehicle 1, and thus a repeated description will beomitted. Hereinafter, as the lawn mowing vehicle, a riding lawn mowingvehicle will be described as an example.

In the present embodiment, two front reel units 13 a and 13 b constitutea first reel unit (electric reel unit). A rear reel unit 14 isconfigured as a second reel unit (electric reel unit).

In the present embodiment, support arms 25 a and 25 b, and electriccylinders 26 a and 26 b constitute a first elevating mechanism thatelevates the front reel units 13 a and 13 b. Further, the rear reel unit14 includes, similar to the front reel units 13 a and 13 b, a frontroller 21, an electric reel (rotating blade) 22, a rear roller (notshown), and a motor 24, and is elevated by an elevating mechanism(second elevating mechanism) (not shown) that includes an electriccylinder (electric actuator) 26 c similar to the electric cylinders 26 aand 26 b.

In the lawn mowing vehicle 4, an “automatic operation mode” thatelevates the front reel units 13 a and 13 b and the rear reel unit 14 incooperation of the front reel units 13 a and 13 b with the rear reelunit 14 and a “manual operation mode” that individually and manuallyelevates the front reel units 13 a and 13 b and the rear reel unit 14are provided as operation modes. A worker operates the display device427, and thereby the “automatic operation mode” or the “manual operationmode” is set.

When the operation mode is set to the “automatic operation mode,” thecontrol device 437 controls the electric cylinders 26 a, 26 b and 26 con the basis of detected results of sensors 34 a to 34 c so thatelevating positions of the front reel units 13 a and 13 b are consistentwith that of the rear reel unit 14. This is intended to realize a highquality of lawn mowing even when a traveling speed of the lawn mowingvehicle 4 automatically varies due to ups and downs of the grounddespite the lawn mowing vehicle 4 being driven so as to have a constanttraveling speed.

The control device 437 calculates a travel distance (travel distancefrom the position at which the front reel units 13 a and 13 b areelevated) by integrating the traveling speed obtained using Equation (1)above from a point of time at which the front reel units 13 a and 13 bare elevated. Then, the control device 437 performs control of elevatingthe rear reel unit 14 at a position at which the calculated traveldistance becomes a distance L between the front reel units 13 a and 13 band the rear reel unit 14. By performing such control, a time from whenthe front reel units 13 a and 13 b begin to be elevated to when the rearreel unit 14 begins to be elevated is changed in response to thetraveling speed. As such, even when the traveling speed is changed, theelevating positions of the front reel units 13 a and 13 b can beconsistent with that of the rear reel unit 14.

Furthermore, the control device 437 controls motor drivers 39 a to 39 cso that the rotational speeds of the electric reels 22 installed on thefront reel units 13 a and 13 b and the rear reel unit 14 areproportional to the traveling speed obtained from Equation (1) or varystep-by-step in relation to the traveling speed obtained from Equation(1). Whether the control is performed so as to be proportional or varystep-by-step in relation to the traveling speed is properly determinedin consideration of, e.g., performance of the motors 24 or the motordrivers 39 a to 39 c.

Next, an operation of the lawn mowing vehicle 4 in the aforementionedconfiguration will be described in brief. The operation of a workerstarting the engine E of the lawn mowing vehicle 4 and driving the lawnmowing vehicle 4 to a position at which a lawn is to be mowed is thesame as in the lawn mowing vehicle 1. Before the lawn is mowed, theworker operates the display device 427 to set the operation mode to the“automatic operation mode” or the “manual operation mode.” FIGS. 6A to6C are views showing one example of displayed contents of the displaydevice 427 provided in the lawn mowing vehicle 4 according to thepresent embodiment. The displayed contents shown in FIGS. 6A to 6C aremerely one example, and the displayed contents or their displaypositions may be appropriately modified.

As shown in FIG. 6A, selection buttons B1 to B3 used to select theoperation mode are displayed on a lower portion of the entire displayregion R of the display device 427. The selection button B1 is a buttonthat sets the operation mode to the “automatic operation mode.” Theselection button B2 is a button that sets the operation mode to a“manual operation mode.” Further, the selection button B3 is a buttonthat sets the operation mode to a “maintenance mode” in which each unitof the lawn mowing vehicle 4 is manually operated so as to perform avariety of maintenance tasks on the lawn mowing vehicle 4.

When a worker operates the selection button B1, the operation modebecomes the “automatic operation mode.” Then, as shown in FIG. 6B, theselection button B1 is erased from the entire display region R, and abutton B11 instructing start and stop of the mowing is displayed. Whenthe worker drives the lawn mowing vehicle 4 to arrive at a position atwhich a lawn is to be mowed and then pushes the button B11 displayed onthe entire display region R of the display device 427, control signalsfrom the control device 437 are output for the switches 38 a and 38 b,and thus the front reel units 13 a and 13 b are lowered. Thereby, thelawn is mowed along the travel path of the lawn mowing vehicle 4 by thefront reel units 13 a and 13 b.

The control device 437 calculates a travel distance by obtaining atraveling speed of the lawn mowing vehicle 4 from the detected result ofthe sensor 34 c (revolutions per minute of the rear wheel 12) usingEquation (1) above and by integrating the obtained traveling speed froma point of time at which the front reel units 13 a and 13 b are lowered.Then, the control device 437 performs control of lowering the rear reelunit 14 at a position at which the calculated travel distance becomesthe distance L between the front reel units 13 a and 13 b and the rearreel unit 14. Thereby, even when the traveling speed is changed, theposition at which the rear reel unit 14 is lowered can be consistentwith that at which the front reel units 13 a and 13 b are lowered.

When the worker pushes the button B11 displayed on the entire displayregion R of the display device 427 again, control signals from thecontrol device 437 are output for the switches 38 a and 38 b, and thusthe front reel units 13 a and 13 b are raised. Thereby, the mowing ofthe lawn by the front reel units 13 a and 13 b is terminated. When thebutton B11 is pushed, the control device 437 calculates a traveldistance by obtaining a traveling speed of the lawn mowing vehicle 4from the detected result of the sensor 34 c (revolutions per minute ofthe rear wheel 12) using Equation (1) above and by integrating theobtained traveling speed, as in the case in which the front reel units13 a and 13 b are lowered. Then, the control device 437 performs controlof raising the rear reel unit 14 at a position at which the calculatedtravel distance becomes the distance L between the front reel units 13 aand 13 b and the rear reel unit 14. Thereby, even when the travelingspeed is changed, the position at which the rear reel unit 14 is raisedcan be consistent with that at which the front reel units 13 a and 13 bare raised.

In the case in which the display shown in FIG. 6A is made by the displaydevice 427, when the worker operates the button B2, the operation modebecomes the “manual operation mode.” Then, as shown in FIG. 6C, thebutton B2 is erased from the entire display region R, buttons B21 andB31 for raising and lowering the front reel unit 13 b, buttons B22 andB32 for raising and lowering the front reel unit 13 a, and buttons B23and B33 for raising and lowering the rear reel unit 14 are displayed.The worker individually operates these buttons. Thereby, the electriccylinders 26 a, 26 b, 26 c, and so on are individually controlled by thecontrol device 437, so that the front reel units 13 a and 13 b and therear reel unit 14 can be individually raised or lowered.

As described above, in the present embodiment, on the basis of thedetected result of, e.g., the sensor 34 c, the traveling speed isobtained and the travel distance is calculated. The control is performedso that the elevating positions of the front reel units 13 a and 13 bare consistent with that of the rear reel unit 14. As such, even whenthe traveling speed of the lawn mowing vehicle 4 is changed, a highquality of lawn mowing is possible. Further, the lawn mowing vehicle 4of the present embodiment is a hybrid type lawn mowing vehicle thattravels using the pressure of the hydraulic pump driven by the power ofthe engine and mows the lawn using the power of the electric motors.Since the lawn mowing vehicle 4 can reduce a risk of oil leakagecompared to a conventional lawn mowing vehicle that mows a lawn usingpower of a hydraulic pump, it can reduce a risk of withering the grasscaused by oil, compared to the conventional lawn mowing vehicle.

(Modification of Fourth Embodiment)

Like the lawn mowing vehicle 2 related to the second embodiment, amodification of the lawn mowing vehicle 4 related to the presentembodiment may be a lawn mowing vehicle 402 that includes a battery B inplace of the engine E, the hydraulic pump 31, and the alternator 32. Inthis case, the lawn mowing vehicle 402 is equipped with a travelingsystem S11 and a steering system S12 in place of the traveling system S1and the steering system S2. Further, the lawn mowing vehicle 402 isequipped with a control device (control unit, speed detection unit) 440in place of the control device 437.

Like the riding lawn mowing vehicle 4 of the fourth embodiment, the lawnmowing vehicle 402 is controlled by the control device 440 so that theelevating positions of the front reel units 13 a and 13 b are consistentwith that of the rear reel unit 14 based on the detected result of,e.g., the sensor 34 c. As such, even when the traveling speed of thelawn mowing vehicle 402 is changed, a high quality of lawn mowing inwhich the grass has a uniform height is possible.

(Fifth Embodiment)

Hereinafter, a fifth embodiment of the present invention will bedescribed based on FIG. 7. The lawn mowing vehicle 5 related to thefifth embodiment of the present invention is similar to the lawn mowingvehicle 1 shown in FIGS. 1 and 2, except that it includes a controldevice 537 in place of the control device 37 shown in FIG. 2 and adisplay device 527 in place of the display device 27 shown in FIG. 2.The lawn mowing vehicle 5 is similar to the lawn mowing vehicle 4related to the fourth embodiment of the present invention in that an“automatic operation mode” and a “manual operation mode” are provided asoperation modes. The present embodiment has a control method differentfrom the fourth embodiment in that, in the “automatic operation mode,”front reel units 13 a and 13 b and a rear reel unit 14 are individuallyelevated. Note that the same symbols are used for constituent elementscommon with the lawn mowing vehicle 1 or 4, and thus a repeateddescription will be omitted.

In the present embodiment, the two front reel units 13 a and 13 b areconfigured as a first reel unit and a second reel unit (electric reelunits). Further, a support arm 25 a and an electric cylinder 26 aconstitute a first elevating mechanism that elevates the front reel unit13 a, whereas a support arm 25 b and an electric cylinder 26 bconstitute a second elevating mechanism that elevates the front reelunit 13 b.

In the present embodiment, the control device 537 controls an operationof a work system S3 of the lawn mowing vehicle 5 in response to aninstruction input via the display device 527, and displays information(e.g., information indicating a traveling speed and rotational speeds ofelectric reels 22) indicating a current state of the lawn mowing vehicle5 on the display device 527. In detail, when instructions to elevate thefront reel units 13 a and 13 b and the rear reel unit 14 are input viathe display device 527, the control device 537 controls ON and OFFstates of, e.g., switches 38 a, 38 b and 38 c, and controls therotational speed of the electric reel of the lowered reel unit among thefront reel units 13 a and 13 b and the rear reel unit 14. Further, apartfrom the instructions to elevate the front reel units 13 a and 13 b andthe rear reel unit 14, an instruction to drive the electric reels 22installed on the front reel units 13 a and 13 b and the rear reel unit14 is given via the display device 527, and the control device 537outputs control signals for motor drivers 39 a to 39 c, and thus therotational speeds of the electric reels 22.

When the operation mode is set to the “automatic operation mode,” thecontrol device 537 controls the electric cylinders 26 a, 26 b and 26 con the basis of detected results of sensors 34 a to 34 c so thatelevating positions of the front reel units 13 a and 13 b are consistentwith that of the rear reel unit 14. This is intended to realize a highquality of lawn mowing even when a traveling speed of the lawn mowingvehicle 5 automatically varies due to ups and downs of the grounddespite the lawn mowing vehicle 5 being driven so as to have a constanttraveling speed. A detailed description will be made below. However,even when the operation mode is set to the “automatic operation mode,”an elevating reel unit may be selected from the front reel units 13 aand 13 b and the rear reel unit 14. As such, for example, any one of thefront reel units 13 a and 13 b may be elevated in cooperation with theelevation of the rear reel unit 14.

In the present embodiment, the rotational speeds of the electric reelsare not necessarily determined only by the traveling speed of the lawnmowing vehicle 5. In addition to the traveling speed of the lawn mowingvehicle 5, the control is performed based on the number of bladesprovided on each electric reel 22 and a mowing pitch (a target height ofthe grass). In detail, assuming that the number of blades of theelectric reel 22 is m [pieces], and the mowing pitch is p [mm], thecontrol device 537 controls the revolutions per minute r [rpm] of theelectric reel 22 such that the revolutions per minute satisfies Equation(3) below.r=(v×10⁶/60)/(m×p)  (3)

where p is the target height of the grass [mm].

Next, an operation of the lawn mowing vehicle 5 in the aforementionedconfiguration will be described in brief. The operation of a workerstarting the engine E of the lawn mowing vehicle 5 and driving the lawnmowing vehicle 5 to a position at which a lawn is to be mowed is thesame as in the lawn mowing vehicle 1 or 4. Before the lawn is mowed, theworker operates the display device 527 to set the operation mode to the“automatic operation mode” or the “manual operation mode.” FIGS. 7A to7D are views showing one example of displayed contents of the displaydevice 527 provided in the lawn mowing vehicle 5 according to thepresent embodiment. The displayed contents shown in FIGS. 7A to 7D aremerely one example, and the displayed contents or their displaypositions may be appropriately modified.

When a worker operates the selection button B1, the operation modebecomes the “automatic operation mode.” Then, as shown in FIG. 7B, thebutton B1 is erased from the entire display region R, and a button B11instructing start and stop of the mowing is displayed. When the workerdrives the lawn mowing vehicle 5 to arrive at a position at which a lawnis to be mowed and then pushes the button B11 displayed on the entiredisplay region R of the display device 527, control signals from thecontrol device 537 are output for the switches 38 a and 38 b and themotor drivers 39 a and 39 b. Thus, the front reel units 13 a and 13 bare lowered and the electric reels 22 of the front reel units 13 a and13 b are rotated. Thereby, the lawn is mowed along the travel path ofthe lawn mowing vehicle 5 by the front reel units 13 a and 13 b.

When the worker pushes the button B11 displayed on the entire displayregion R of the display device 527 again, control signals from thecontrol device 437 are output for the switches 38 a and 38 b and themotor drivers 39 a and 39 b. Thus, the front reel units 13 a and 13 bare raised, and the electric reels 22 of the front reel units 13 a and13 b are stopped. Thereby, the mowing of the lawn by the front reelunits 13 a and 13 b is terminated. When the button B11 is pushed, thecontrol device 537 calculates a travel distance by obtaining a travelingspeed of the lawn mowing vehicle 5 from the detected result of thesensor 34 c (revolutions per minute of the rear wheel 12) using Equation(1) above and by integrating the obtained traveling speed, as in thecase in which the front reel units 13 a and 13 b are lowered. Then, thecontrol device 537 performs control of raising the rear reel unit 14 ata position at which the calculated travel distance becomes the distanceL between the front reel units 13 a and 13 b and the rear reel unit 14.Thereby, even when the traveling speed is changed, the position at whichthe rear reel unit 14 is raised can be consistent with that at which thefront reel units 13 a and 13 b are raised.

In the case in which the display shown in FIG. 7A is made by the displaydevice 527, when the worker operates the button B3, the operation of thelawn mowing vehicle 5 enters a “maintenance mode.” Then, as shown inFIG. 7D, the button B3 is erased from the entire display region R, andbuttons B41 to B43 that select an elevating reel unit (an operating reelunit) among from the front reel units 13 a and 13 b and the rear reelunit 14 are displayed. Now, the case in which a width of the lawn to bemowed is a width mowed by the front reel unit 13 a and the rear reelunit 14, and in which the front reel unit 13 b need not be used to mowthe lawn will be taken into consideration. In such a case, the workeroperates a button B42 and a button B43 shown in FIG. 7D to select onlythe front reel unit 13 a and the rear reel unit 14.

After the aforementioned selection is made, when the worker operates theselection button B1, the operation mode becomes the “automatic operationmode,” and the button B11 shown in FIG. 7B is displayed. Then, when theworker pushes the button B 11, only the front reel unit 13 a notselected to be in the maintenance mode is lowered by the control of thecontrol device 53, and the electric reel 22 of the front reel unit 13 ais rotated. Thereby, the lawn is mowed by the front reel unit 13 a. Inthis case, the electric reel 22 of the front reel unit 13 b is stillstopped.

Then, the control device 537 performs control of lowering the rear reelunit 14 to rotate the electric reel 22 of the rear reel unit 14 at aposition at which the travel distance from a position at which the frontreel unit 13 a is lowered becomes the distance L between the front reelunits 13 a and 13 b and the rear reel unit 14. Due to this control, theposition at which the rear reel unit 14 is lowered can be consistentwith that at which the front reel unit 13 a is lowered.

Afterwards, when the worker pushes the button B11 again, control ofraising the front reel unit 13 a and control of stopping the electricreel 22 of the front reel unit 13 a are performed by the control device537. Then, the control device 537 performs control of raising the rearreel unit 14 to rotate the electric reel 22 of the rear reel unit 14 ata position at which the travel distance from a position at which thefront reel unit 13 a is raised becomes the distance L between the frontreel units 13 a and 13 b and the rear reel unit 14. Thereby, theposition at which the rear reel unit 14 is raised can be consistent withthat at which the front reel unit 13 a is raised.

In the case in which the display shown in FIG. 7A is made by the displaydevice 527, when the worker operates the button B2, the operation modebecomes the “manual operation mode.” Then, as shown in FIG. 7C, thebutton B2 is erased from the entire display region R, buttons B21 andB31 for raising and lowering the front reel unit 13 b, buttons B22 andB32 for raising and lowering the front reel unit 13 a, and buttons B23and B33 for raising and lowering the rear reel unit 14 are displayed.The worker individually operates these buttons. Thereby, the electriccylinders 26 a, 26 b, 26 c, and so on are individually controlled by thecontrol device 537, so that the front reel units 13 a and 13 b and therear reel unit 14 can be individually raised or lowered.

As described above, in the present embodiment, the front reel units 13 aand 13 b and the rear reel unit 14 are individually elevated. Thereby,the mowing width can be freely changed depending on the lawn to bemowed. Thereby, a portion of the lawn which is mowed several times canbe reduced, and a high quality of lawn mowing is possible. Further, thelawn mowing vehicle 4 of the present embodiment is a hybrid type lawnmowing vehicle that travels using the pressure of the hydraulic pumpdriven by the power of the engine and mows the lawn using the power ofthe electric motors. Since the lawn mowing vehicle 4 can reduce a riskof oil leakage compared to a conventional lawn mowing vehicle that mowsa lawn using power of a hydraulic pump, it can reduce a risk ofwithering the grass caused by oil, compared to the conventional lawnmowing vehicle. Furthermore, the elevation of the front reel units 13 aand 13 b and the rear reel unit 14 and the rotation of the electricreels 22 installed on these reel units can be precisely controlled, andthus consumption power can be reduced.

(Modification of Fifth Embodiment)

Like the lawn mowing vehicle 2 related to the second embodiment, amodification of the lawn mowing vehicle 5 related to the presentembodiment may be a lawn mowing vehicle 502 that includes a battery B inplace of the engine E, the hydraulic pump 31, and the alternator 32. Inthis case, the lawn mowing vehicle 502 is equipped with a travelingsystem S11 and a steering system S12 in place of the traveling system S1and the steering system S2. Further, the lawn mowing vehicle 502 isequipped with a control device (control unit, speed detection unit) 540in place of the control device 537.

Like the riding lawn mowing vehicle 5 of the fifth embodiment, the lawnmowing vehicle 502 is also configured so that the elevations of thefront reel units 13 a and 13 b and the rear reel unit 14 areindividually controlled by the control device 540. Further, the lawnmowing vehicle 502 is controlled by the control device 540 so that theelevating positions of the front reel units 13 a and 13 b are consistentwith that of the rear reel unit 14 based on the detected result of,e.g., the sensor 34 c. As such, even when the traveling speed of thelawn mowing vehicle 502 is changed, or even when the width at which thelawn is to be mowed is narrow, a high quality of lawn mowing in whichthe grass has a uniform height is possible.

Further, like the lawn mowing vehicle 5, since the elevation of thefront reel units 13 a and 13 b and the rear reel unit 14 and therotation of the electric reels 22 installed on these reel units can beprecisely controlled, consumption power can be reduced.

Further, sensors detecting the state of the lawn are installed on thefront reel units 13 a and 13 b and the rear reel unit 14, respectively.On the basis of detected results of the sensors, the control device 540may control whether or not to rotate the electric reels 22 installed onthe front reel units 13 a and 13 b and the rear reel unit 14.

Due to this control, the lawn mowing vehicle travels only in the statein which all of the front reel units 13 a and 13 b and the rear reelunit 14 are lowered, and thereby the electric reels 22 installed on thefront reel units 13 a and 13 b and the rear reel unit 14 areautomatically rotated or stopped depending on the height of the grass.As such, only the grass required to be mowed can be mowed. The sensordetecting the state of the lawn may include a height detection sensorthat detects the height of the grass using, e.g., a laser sensor, or avisual sensor that performs image processing on a captured image andmonitors the state of the lawn.

Further, the aforementioned embodiment has been described regarding theexample in which the worker operates the display device 527, and therebythe elevating reel unit is selected from among the front reel units 13 aand 13 b and the rear reel unit 14. However, a mechanical button orlever for selecting the reel unit may be installed, and the worker mayoperate the button or lever. Thereby, the elevating reel unit may beselected.

INDUSTRIAL APPLICABILITY

In the present invention, the motors are controlled depending on thedetected results of the speed detection units, and thereby therotational speeds of the rotating blades installed on the electric reelunits are controlled. Further, the first and second elevating mechanismsare controlled depending on the detected results of the speed detectionunits so that the elevating positions of the first reel units areconsistent with that of the second reel unit. Furthermore, the controlunit can control the first and second elevating mechanisms, each ofwhich has the electric actuator, to individually elevate the first andsecond reel units, and elevate and operate a minimum necessary reel unitto mow the lawn. Thereby, the high quality of lawn mowing is possible.Further, in the present invention, the state of the lawn mowed by therotating blade is detected by the detection sensor, and a predeterminedprocess is performed on the detected result of the detection sensor.Thereby, the growth data indicating the growth situation of the lawn isgenerated. The generated growth data is displayed on the display unit.Thereby, it is possible to provide a higher value-added lawn mowingvehicle that can provide useful information in managing the lawn.

BRIEF DESCRIPTION OF THE REFERENCE SYMBOLS

1, 2, 3, 302, 4, 402, 5, 502: LAWN MOVING VIHICLE

13 a, 13 b, 313 a, 313 b: FRONT REEL UNIT

14, 314: REAR REEL UNIT

22: ELECTRIC REEL

24: MOTOR

27, 327, 427, 527: DISPLAY DEVICE

34 a to 34 c: SENSOR

37, 40, 437, 440, 537, 540: CONTROL DEVICE

The invention claimed is:
 1. A lawn mowing vehicle that mows a lawnalong a travel path, comprising: at least three wheels; at least oneelectric reel unit having a rotating blade driven by a motor; a speeddetection unit detecting a number of revolutions per minute of at leastone of the wheels of the vehicle; and a control unit that controls themotor depending on the detected result of the speed detection unit,thereby controlling a rotational speed of the rotating blade installedon the electric reel unit, wherein the rotating blade is configured sothat a rotational shaft thereof is set in a leftward/rightward directionof the vehicle with respect to a traveling direction, and the controlunit obtains the traveling speed of the vehicle on the basis of thenumber of revolutions per minute of at least one of the wheels of thevehicle detected by the speed detection unit and on the basis of aneffective diameter of the at least one of the wheels, the travelingspeed v, in kilometers per hour, of the vehicle obtained by the controlunit, based upon one wheel of the vehicle, being given by theexpression:v=(d/10⁶)×π×60×n, n being the number of revolutions per minute of theone wheel detected by the speed detection unit and d being an effectivediameter of the one wheel in millimeters.
 2. The lawn mowing vehicleaccording to claim 1, wherein, the at least one of the wheels comprisesa plurality of wheels and when the revolutions per minute of each of theplurality of wheels of the vehicle are different, the control unitobtains an average value of the revolutions per minute of the pluralityof wheels.
 3. The lawn mowing vehicle according to claim 1, wherein thecontrol unit controls a rotational speed of the rotating blade on thebasis of a number of blades of the electric reel unit and a mowing pitchof the lawn which is arbitrarily set in advance, in addition to thetraveling speed obtained by the control unit.
 4. The lawn mowing vehicleaccording to claim 1, wherein the control unit controls a rotationalspeed of the rotating blade so that the rotational speed of the rotatingblade is proportional to the traveling speed obtained by the controlunit.
 5. The lawn mowing vehicle according to claim 1, wherein thecontrol unit controls a rotational speed of the rotating blade so thatthe rotational speed of the rotating blade varies step-by-step withrespect to the traveling speed obtained by the control unit.
 6. The lawnmowing vehicle according to claim 3, wherein the control unit controlsthe rotational speed of the rotating blade, r, in revolutions perminute, so that the value of r is given by the following expression:r=(v×10⁶)/(m×p), m being the number of blades of the electric reel unit,and p being the mowing pitch of the lawn in millimeters.